Field
Embodiments disclosed herein generally relate to the manufacture of polishing articles utilized in chemical mechanical polishing (CMP) processes. More specifically, embodiments disclosed herein are related to compositions of materials and methods of manufacturing polishing articles.
Description of the Related Art
Chemical-mechanical polishing (CMP), also known as chemical mechanical planarization, is a process used in the semiconductor fabrication industry to provide flat surfaces on integrated circuits devices. CMP involves pressing a rotating wafer against a rotating polishing pad, while applying polishing fluid or slurry to the pad to affect removal of films or other materials from a substrate. Such polishing is often used to planarize insulating layers, such as silicon oxide and/or metal layers, such as tungsten, aluminum, or copper, that have been previously deposited on the substrate.
The polishing process results in “glazing” or smoothening of the pad surface, which reduces film removal rate. The surface of the polishing pad is “roughened” or conditioned to restore the pad surface which enhances local fluid transport and improves removal rate. Typically, conditioning is performed, in between polishing two wafers or in parallel with polishing the wafer, with a conditioning disk coated with abrasives such as micron sized industrial diamonds. The conditioning disk is rotated and pressed against the pad surface and mechanically cuts the surface of the polishing pad. However, while the rotation and/or down force applied to the conditioning disk is controlled, the cutting action is relatively indiscriminate, and the abrasives may not cut into the polishing surface evenly, which creates a differential in surface roughness across the polishing surface of the polishing pad. As the cutting action of the conditioning disk is not readily controlled, the pad lifetime may be shortened. Further, the cutting action of the conditioning disk sometimes produces large asperities in the polishing surface, along with pad debris. While the asperities are beneficial in the polishing process, the asperities may break loose during polishing, which creates debris that, along with pad debris from cutting action, contributes to defects in the substrate.
Numerous other methods and systems that act on the polishing surface of the polishing pad have been performed in an attempt to provide uniform conditioning of the polishing surface. However, control of the devices and systems (e.g., cutting action, down force, among other metrics) remain unsatisfactory and may be frustrated by the properties of the polishing pad itself. For example, properties such hardness and/or density of the pad material may be non-uniform, which leads to more aggressive conditioning on some portions of the polishing surface relative to other portions.
Therefore, there is a need for a polishing article having properties that facilitate uniform polishing and conditioning.